Valves, having resilient cores, have been in use for many years for the purpose of permitting the introduction of probes from a low pressure areas into high pressure, areas within pressure vessels. For example, among the most notorious are those valves utilized for filling such items as footballs, basketballs, and volleyballs with air. Also, such valves are frequently used to insert a pressure test probe that indicates the pressure within the ball to determine whether or not it is properly inflated.
Other valve/test plugs are illustrated in U.S. Pat. No. 3,902,517 issued Sept. 2, 1975 to Richard Hastwell. That patent describes a valve core of resilient material that is located in the filler cap of a fuel tank wherein an inflating needle can be inserted therethrough to pressurize a fuel supply.
Another patent illustrating a resilient valve core is shown in U.S. Pat. Des. No. 252,701 issued Aug. 21, 1979 to Jerry L. Caldwell. The various figures of that design patent illustrate a resilient core for use in such valve test plugs and the like.
U.S. Pat. No. 3,797,317 issued Mar. 19, 1974 to Charles D. Peterson, Jr. discloses a split valve test plug that is intended for the same purposes as described in connection with this valve. As shown and described therein, the core of that valve consists of two separate members located in the body of the valve with each having a split therethrough for receiving a test probe. Stated another way, the valve of that patent utilizes two separate valve members, each of which seals on the probe when it is inserted therethrough. The lower valve closes first when the probe is being removed to aid in securely closing the upper or outer valve member. As described therein, the two valve members of the '317 patent are identically constructed. Also disclosed therein is a cap or cover that carries an internal gasket for sealing on the upper end of the valve body when the probe is removed to assure that no leakage occurs even if one of the two valve members should leak.
While the foregoing have worked satisfactorily, some problems have arisen. For example, the valve caps and the seal contained therein are loose and are frequently lost or damaged when the probe is inserted through the valve.
The seals in the caps have disintegrated due to screwing the caps onto the body too tightly with the result that the valve cores have been damaged or dislodged into the vessel when attempting to insert a test probe through the core. The result of the loss of a valve core entails the release of whatever pressure is in the vessel through the test plug.
In addition, the use of identical valve core members results in a compromise in the hardness of the valve core members. Such a compromise may result in extrusion or severe deformation of the core member exposed to the higher pressure if the core members are too soft. The compromise may result in severe leakage problems if the core members fail to seal properly on the probe because the members are too hard.